Argentine J A, James A A
Department of Molecular Biology and Biochemistry, University of California, Irvine 92717, USA.
Insect Biochem Mol Biol. 1995 May;25(5):621-30. doi: 10.1016/0965-1748(94)00103-o.
Esterase enzymatic activity was investigated in salivary gland lysates of adult Aedes aegypti. Esterases in lysates made from female glands had higher specific activity than those in lysates from male glands towards beta-naphthyl acetate but showed no difference with alpha-naphthyl butyrate as a substrate. Female salivary gland lysates showed no difference in activity to alpha- and beta-forms of naphthyl acetate and no discernable activity towards alpha-naphthyl caprate. Both female and male salivary gland lysates exhibited phosphatase enzymatic activity but the specific activities were lower than those seen for the esterase enzymatic activity. Salivary gland esterase activity was inhibited completely by paraoxon, para-hydroxymercurobenzoate, tetraethylammonium iodide and moderately by diisopropylfluorophosphate. Eserine and phenylmethylsulfonylfluoride had no effect on enzyme activity. In a probing assay, adults of both sexes were shown to secrete esterase in saliva. Esterase activity was present in the saliva of females probing for either a sugar meal or a blood meal. Furthermore, esterase was secreted from female salivary glands in culture. Histochemical analysis of dissected salivary glands showed that the majority of the esterase enzymatic activity was in the distal-lateral lobes of the female tissues, although the proximal-lateral and medial lobes also had activity. Male salivary glands stained uniformly over all of the lobes. A salivary gland-specific esterase, designated SG-EST, appears to account for the majority of enzyme activity in the glands. SG-EST was partially purified by electroelution of an active protein from native polyacrylamide gels, and has an approximate molecular weight of 65,000 Da. In separate experiments, affinity chromatography independently identified a single 65,000 Da protein likely to be SG-EST. Native electrophoretic analysis of salivary glands revealed that, while most enzyme activity is due to SG-EST, there are two other esterases present. One of these minor moieties is present in adult tissues in addition to the salivary gland, and the other is present throughout development. Possible functions of the salivary gland esterase are discussed.
在成年埃及伊蚊的唾液腺裂解物中研究了酯酶的酶活性。用雌性腺体制成的裂解物中的酯酶对乙酸β-萘酯的比活性高于用雄性腺体制成的裂解物中的酯酶，但以丁酸α-萘酯为底物时无差异。雌性唾液腺裂解物对乙酸萘酯的α型和β型的活性无差异，对癸酸α-萘酯无明显活性。雌性和雄性唾液腺裂解物均表现出磷酸酶活性，但比活性低于酯酶活性。唾液腺酯酶活性被对氧磷、对羟基汞苯甲酸、碘化四乙铵完全抑制，被二异丙基氟磷酸中度抑制。毒扁豆碱和苯甲基磺酰氟对酶活性无影响。在一项探测试验中，两性成虫均被证明在唾液中分泌酯酶。在取食糖或血液的雌性唾液中存在酯酶活性。此外，在培养中雌性唾液腺分泌酯酶。对解剖的唾液腺的组织化学分析表明，大部分酯酶活性存在于雌性组织的远外侧叶，尽管近外侧叶和中叶也有活性。雄性唾液腺在所有叶上均匀染色。一种唾液腺特异性酯酶，命名为SG-EST，似乎是腺体中大部分酶活性的原因。通过从天然聚丙烯酰胺凝胶中电洗脱活性蛋白对SG-EST进行了部分纯化，其分子量约为65,000 Da。在单独的实验中，亲和层析独立鉴定出一种可能是SG-EST的单一65,000 Da蛋白。唾液腺的天然电泳分析表明，虽然大部分酶活性归因于SG-EST，但还存在另外两种酯酶。这些次要成分之一除了唾液腺外还存在于成虫组织中，另一种在整个发育过程中都存在。讨论了唾液腺酯酶的可能功能。
